Lithostratigraphic Framework and Production History of Wilcox in Central Louisiana: ABSTRACT

Abstract

Complex fluvial, deltaic, and marine sedimentary processes active during deposition of the Wilcox Group in central Louisiana created multiple, discontinuous sandstones. Prolific hydrocarbon reservoirs developed in association with positive structural features or where sedimentary characteristics were favorable. Because the Wilcox Group contains numerous complex depocenters, it does not lend itself to easy regional correlation. Therefore, to better delineate the occurrence of hydrocarbon-bearing sediments and to promote further exploration, five-fold lithostratigraphic framework is proposed for the Wilcox Group in Louisiana. Five lithostratigraphic zones were defined on the basis of sedimentary processes and resistivity-log character. Their thickness and sand content were mapped within 21 parishes. These zones vary from 115 to 1,000 ft thick and the sand content in each ranges from 25 to 60%. All zones produce hydrocarbons, although production is geographically variable. Production in the updip Wilcox is by far the greatest in Zone III, whereas Zone I and Zone II are most productive in the downdip deep Wilcox shelf-margin trend, a paleo-shelf margin. Isopach and isolith maps indicate that the Wilcox was sourced from the northeast and northwest. All zoness display a strong north-south isopach grain in the northern two-thirds of the study area. East-west-oriented sand packages are presentedmore » southward along the paleo-shelf margin. Regional mapping facilitated the extension of presently existing production from fluvial/deltaic depocenters by following the sand packages to the west and southwest. Where these sandstones are associated with favorable structural/stratigraphic trapping conditions, new and lucrative Wilcox fields should be found.« less